1. Field of the Invention
This invention relates to the field of ribbon printing devices, and more particularly to those devices that utilize multicolored ribbons with means for automatically re-coating the ribbon with ink during operation.
2. Background Art
In ribbon printing devices, the quality of the printing is greatly affected by the condition of the ribbon supply. The printing quality is improved with a ribbon that has not been used before. Ideally, one would use a ribbon once such that the ribbon would increment throughout the ribbon supply with each character that was printed. When the ribbon had incremented to the end of the supply, the ribbon would be discarded.
With this method, ribbon supplies are replaced frequently. For ease of use, ribbons are typically supplied in cartridges that are easily replaceable onto the printhead carrier of the printer. When the ribbon has been fed through the printhead once, the cartridge of used ribbon is discarded and replaced with a new cartridge supply of freshly inked ribbon.
Although it is convenient to replace a ribbon cartridge onto the print carrier, this ribbon cartridge adds excessive mass to the printhead carrier. This extra mass slows the response time and movement of the printhead carrier.
Additionally, the frequent replacement of ribbon cartridges has become somewhat costly. It is known that by extending the useful life of the ribbon, this expense can be reduced. One way to extend the useful life of a ribbon is to re-ink a continuous ribbon after each use. Such a device for replenishing marking fluid to a ribbon typically comprises a rotatable roll impregnated with a marking fluid such as ink.
A problem with common ink replenishing devices results from the non-constant feed rate of the ribbon through the printhead due to the different amounts of ribbon utilized during the printing and non printing modes of the printhead. Because of this, the replenishing device may supply ink to the ribbon in an uneven fashion. Consequently, the printing quality will become degraded as the printing varies in lightness and darkness with the varying amounts of ink on the ribbon.